In recent years, thermal transfer systems have been developed to obtain prints from pictures which have been generated electronically from a color video camera. According to one way of obtaining such prints, an electronic picture is first subjected to color separation by color filters. The respective color-separated images are then converted into electrical signals. These signals are then operated on to produce cyan, magenta and yellow electrical signals. These signals are then transmitted to a thermal printer. To obtain the print, a cyan, magenta or yellow dye-donor element is placed face-to-face with a dye-receiving element. The two are then inserted between a thermal printing head and a platen roller. A line-type thermal printing head is used to apply heat from the back of the dye-donor sheet. The thermal printing head has many heating elements and is heated up sequentially in response to the cyan, magenta and yellow signals. The process is then repeated for the other two colors. A color hard copy is thus obtained which corresponds to the original picture viewed on a screen. Further details of this process and an apparatus for carrying it out are contained in U.S. Pat. No. 4,621,271 by Brownstein entitled "Apparatus and Method For Controlling A Thermal Printer Apparatus," issued Nov. 4, 1986, the disclosure of which is hereby incorporated by reference.
Thermal dye transfer as described above is a well-established procedure for production of an image in a polymeric receiver sheet. There are certain physical requirements, some quite severe, relative to thickness, flatness, flexibility, and shape of such receivers when used in thermal head, laser, flash, or other thermal printing devices. Such restrictions limit the applicability of thermal dye transfer to non-planar objects. It would be desirable to have a process whereby an image generated by a thermal printing device could be formed on an object with few, if any, restrictions of thickness, flatness, shape and flexibility.
Japanese Kokais 62-66997 (Nitto Electric Ind. Co. LTD) and 60-203494 (Ricoh K. K.) disclose forming images in a transparent receiver by thermal dye transfer and then adhering the receiver to an object/mount. This makes possible forming thermal dye transfer images on a wider variety of objects than direct thermal dye transfer to the object, but the presence of an adhered receiver is objectionable in that it results in a raised surface appearance.
EP 0 266 430 (Dai Nippon Insatsu K. K.) discloses a process for formation of a dye transfer image on an arbitrary object comprising forming an image in a dye-receiving layer of a transferrable sheet, separating the dye image-receiving layer from its support, and adhering the dye image-receiving layer to the arbitrary object. By separating the image-receiving layer from its support, a thinner receiver is adhered to the object. While this approach may reduce objections to a raised surface appearance due to the adhered layer, there is still the problem of adhering the dye image containing layer permanently to the object.
It would be desirable to provide a process whereby a thermal dye transfer image could be formed on an object of arbitrary shape without having to adhere a separate layer to such objects.